Biomedical Engineering Reference
In-Depth Information
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Figure 10.4
TEM images of the thin sections of (a) bare and (b) and (c) PAH-
stabilized magnetic nanoparticles coated C. pyrenoidosa cells.
Reproduced, with permission, from Ref. 40.
for magnetic resonance imaging based on dextran-coated monocrystalline
iron oxide nanoparticles (MION). Different derivatives of iron oxides nano-
particles were used for cell labeling to track their migration in vivo. Super-
paramagnetic MION are widely used because of their small size (4-7 nm) and
their known magnetic and biochemical properties, which enable the con-
trast agent to be shuttled into the cell; nanoparticles can be taken up by cells
during cultivation by endocytosis. Dendrimer-encapsulated super-
paramagnetic iron oxides have also been used for magnetic labeling and
in vivo tracking of stem cells.
41,42
Another protocol for rapid magnetic modification of leukemia K562 cells
via their decoration with cationic magnetic nanoparticles (CMNPs) has been
developed. The CMNPs (3-aminopropyltriethoxysilane-treated Fe
3
O
4
) were
synthesized; after the incubation of precultured leukemia K562 cells in the
presence of CMNPs for a period of time, the CMNPs-modified living cells
were prepared. In the next step, these cells were rapidly isolated from the
medium and immobilized firmly on the electrode surface via a magnetic
field.
43
In another procedure (poly)allylamine hydrochloride (PAH) stabilized
positively charged magnetic nanoparticles (average diameter around 15 nm)
were prepared using a simple synthesis. HeLa cells were magnetically la-
beled with the particles after 3 min of incubation. High-magnification SEM
images demonstrate that the nanoparticles are concentrated as a monolayer
on the surface of the cell.
44
Magnetic cell labeling has also been employed during the magnetofection
process. Magnetofection is a simple and highly ecient transfection method
that uses magnetic fields to concentrate magnetic particles containing nu-
cleic acid into the target cells. Magnetofection is based on three steps: for-
mulating a magnetic vector, its addition to the medium covering cultured
cells and applying a magnetic field in order to direct the vector towards the
target cells. The simplest approach to form magnetic derivatives of nucleic
acids employs magnetic nanocomposites covered with charged biocompat-
ible polymers that enable formation of ionic complexes with nucleic acids.
.
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